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Create files and directories

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As a developer at Tailwind Traders, you're about to dive into the practical use of creating and deleting new files and directories programmatically. This is a common requirement for line-of-business applications.

So far, you've learned how to work with files and directories by using the fs module. You can also use the fs module to create, delete, copy, move, and otherwise manipulate files and directories on a system programmatically.

Create directories with fs.mkdir

The mkdir method allows creation of directories. The following method creates a folder called newDir inside the 201 folder.

const fs = require("fs").promises;
const path = require("path");

await fs.mkdir(path.join(__dirname, "stores", "201", "newDir"));

The file structure /stores/201 must already exist, or this method fails. You can pass in an optional recursive flag if the file structure doesn't exist and you want the operation to create it.

await fs.mkdir(path.join(__dirname, "newDir", "stores", "201", "newDir"), {
  recursive: true
});

Make sure directories exist

If the directory you're trying to create already exists, the mkdir method throws an error. That situation isn't good because the error causes your program to stop abruptly. To avoid that situation, Node.js recommends you wrap the mkdir method in a try/catch if you plan (as we do) to manipulate the file or directory after you open it.

const pathToCreate = path.join(__dirname, "stores", "201", "newDirectory");

// create the salesTotal directory if it doesn't exist
try {
  await fs.mkdir(salesTotalsDir);
} catch {
  console.log(`${salesTotalsDir} already exists.`);
}

Create files with fs.writeFile

You can create files by using the fs.writeFile method. This method takes in a path to the file, and the data that you want to write to the file. If the file already exists, it's overwritten.

For instance, this code creates a file called greeting.txt with the text "Hello World!" inside.

const pathToFile = path.join(__dirname, "greeting.txt");
await fs.writeFile(pathToFile, "Hello World!");

If you omit the last parameter, which is the data to be written to the file, Node.js writes "undefined" to the file. That situation is probably not what you would ever want. To write an empty file, pass an empty string. An even better option would be to pass the String function, which effectively does the same thing without leaving empty quotes in your code.

const pathToFile = path.join(__dirname, "greeting.txt");
await fs.writeFile(pathToFile, String());

In the next exercise, you'll use your knowledge of how to create files and directories to extend the program to create a directory that will store the total of all sales files.

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